Ohta Koukan Co.

Nishi-Tokyo-shi, Japan

Ohta Koukan Co.

Nishi-Tokyo-shi, Japan

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Sasaki K.,Hiroshima Kokusai Gakuin University | Morikawa H.,Hiroshima Kokusai Gakuin University | Kishibe T.,Hiroshima Kokusai Gakuin University | Mikami A.,Ohta Koukan Co. | And 2 more authors.
Bioscience, Biotechnology and Biochemistry | Year: 2012

About 90% of the radioactive Cs in the sediment mud of a school's swimming pool in Fukushima, Japan was removed by treatment for 3 d using the alginate immobilized photosynthetic bacterium Rhodobcater sphaeroides SSI. Even though batch treatment was carried out 3 times repeatedly, the activity of immobilized cells in removing Cs was maintained at levels of about 84% (second batch) and 78% (third batch). Cs was strongly attached to the sediment mud because, even with HNO3 treatment at pH of 2.00-1.60 for 24 h, it was not eluted into the water. Furthermore, more than 75% of the Cs could be removed without solubilization with HNO3. This suggests that the Cs attached to the sediment mud was transformed into immobilized cells via the Cs+ ion by the negative charge of the immobilized cell surface and/or the potassium transport system of the photosynthetic bacterium.


Sasaki K.,Hiroshima Kokusai Gakuin University | Morikawa H.,Hiroshima Kokusai Gakuin University | Kishibe T.,Hiroshima Kokusai Gakuin University | Takeno K.,Hiroshima Kokusai Gakuin University | And 3 more authors.
Bioscience, Biotechnology and Biochemistry | Year: 2012

Practical removal of radioactivity from polluted soil in Fukushima, Japan was done using a photosynthetic bacterium, Rhodobacter sphaeroides SSI, immobilized in alginate beads. The beads were put in a mesh bag and soaked in which soil was suspended (5 kg of soil/ 10 L of tap water). The radioactivity of the broth decreased by 31% after 15 d of aerobic treatment. When lactic acid bacterial culture broth was added to the suspend broth, about 50% of the radioactivity was transferred to a suspend broth fraction consisting of small particles from the soil after 3 d of fermentation and 20 s of sedimentation. The results suggest that organic matter in the soil was decomposed by anaerobic digestion and lactic acid fermentation simultaneously, and was then transferred into the liquid as small particles. With combined treatment by anaerobic digestion and lactic acid fermentation for 5 d and immobilized bead aerobic treatment for an additional 19 d, the radioactivity of suspend broth decreased by 66%. The radioactivity of the original soil (10.56μSv/h) ultimately decreased by 67% (3.52μSv/h) after the combined treatment.


Sasaki K.,Hiroshima Kokusai Gakuin University | Kishibe T.,Hiroshima Kokusai Gakuin University | Takeno K.,Hiroshima Kokusai Gakuin University | Mikami A.,Ohta Koukan Co. | And 2 more authors.
Seibutsu-kogaku Kaishi | Year: 2013

Removal of radionuclides (U, Sr, Co) and toxic metals (Hg, Pb, Cr, Cd, As) was carried out by using a photosynthetic bacterium, Rhodobacter sphaeroides SSI strain immobilized on pieces of porous ceramic, which were recovered by an electromagnet. Almost complete removal (100%) of U, removal of 82% of Sr, 58% of Co and almost complete removal (100%) of toxic metals, were observed after 2-4 days of aerobic treatment in synthetic sewage wastewater. Using the immobilized SSI strain on porous ceramic made from waste glass, simultaneous removal of Cs and Sr was carried out. Outdoor experiments, performed in a vessel measuring 1 m3, resulted in almost complete (100%) removal of Cs, and 61% removal of Sr after 2-3 days. Removal of radioactive Cs from a swimming pool of a school of Fukushima City was carried out by using alginate immobilized SSI beads (about 2 cm in diameter). About 90% of radioactive Cs in mud (sediment) accumulated at the bottom of the swimming pool was removed after 3 days of aerobic treatment. These beads were used consecutively in the experiments at least 3 times. Beads experienced a reduction in both weight and mass by 99.3% and 97.3%, respectively, after low temperature drying and incineration, at about 600°C, without ever releasing any radioactivity into the atmosphere. Lactic acid fermentation and anaerobic digestion of soil, polluted by radioactive Cs from Fukushima, was carried out, as a pre-treatment. Thereafter, SSI immobilized bead treatment was carried out as an additional treatment. About 70% radioactive Cs was removed from polluted soil, after 19 days of additional treatment. Thus, a practical and effective removal of radioactive Cs from polluted soil was demonstrated by alginate immobilized SSI strain in combination with lactic acid fermentation and anaerobic digestion.

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